GeoRSS/RSS Feed Reader/Writer

XML feeds are a popular method of publishing information to a set of subscribers. Using GeoRSS, an XML feed can be extended to include spatial data.

The GeoRSS reader/writer plug-in enables FME to read and write XML feeds and their spatial data extensions.

Overview

An XML feed can be in one of several different formats, with the most common formats being RSS and Atom. Both of these formats have a similar structure in that the feed contains metadata and a collection of entries. The specifications for the current versions of these formats can be found at http://www.rssboard.org/rss-specification and http://tools.ietf.org/html/rfc4287, respectively.

Currently the GeoRSS reader supports RSS versions 0.91, 0.92 and 2.0, as well as Atom 0.3 and 1.0. The GeoRSS writer can output feeds in RSS 2.0 or Atom 1.0.

The GeoRSS specification defines a way to add spatial information to an XML feed. The GeoRSS reader and writer both support each of the three methods used to include spatial information: W3C Geo, GeoRSS Simple, and GML. Specifications for each of these methods can be found at http://www.georss.org.

Reader Overview

The GeoRSS reader works by mapping an XML feed and its entries into FME features. A single FME feature is created for the feed metadata, and a FME feature is created for each entry in the feed. Because each feed format has a similar structure, the same schema is used for every feed that the reader processes, regardless of the feed format and version. The reader can handle an XML feed from a local or network file, or a remote URL accessible via http or ftp. The reader can access these URL’s directly, or it can be routed through a proxy server.

Writer Overview

The GeoRSS writer can write any collection of features out as a GeoRSS feed. If no feature is specified to be a Feed type feature, then the writer will use default values for the metadata it produces. Any feature whose type is not ‘Feed’ will be treated as an ‘Entry’ type feature.

This means that the writer will look at features for the attributes specified by the GeoRSS schema. Any feature attributes which are not contained in the GeoRSS feature schema will be ignored. Furthermore, if a feature has no value for certain attributes, the GeoRSS writer will provide default values for these attributes. This ensures that the GeoRSS writer always tries to produce a valid Atom or RSS feed, regardless of the features that are passed to it.